Flotation concentration



Patented July 29, 1930 UNITE STATES PATENT OFFICE ROBERT E. PHELAN AND SHERWIN P. LOWE, OF DENVER, COLORADO, ASSIG-NORS TO ROSCOE I-I. CHANNING, JR., AGENT, OF SAN FRANCISCO, CALIFORNIA FLOTATION CONCENTRATION No Drawing. Original application filed October 18, .1927, Serial No. 227,048. Divided and this application filed October 11, 1928. Serial No. 311,962.

Our invention relates to a process for use in the flotation of ores. In many sulphide ores which are amenable to flotation, there are various percentages of mica, talc or other micaceous or talcy minerals which float more or less readily and thereby the grade of the concentrates is lowered. These minerals may otherwise-be an undersirable constituent of the concentrates.

This application is a division of a co-pending application Ser. N o. 227,048'filed Oct. 18, 1927, now Patent 1,690,907, granted Nov. 6, 1928.

One method that has been disclosed of depressing mica and thereby preventing it from entering the froth is by the use of starch. We have discovered however that the starch acts in various ways, depending upon the condition of the pulp from which the forth concentrat is obtained, sometimes not depressing the mica at all but, on the contrary, in certain cases, aiding it to float. Under some circumstances, this is an end very greatly desired.

We have discovered the following princistarch and the usual flotation reagents will not prevent themica from entering the froth, but if the starch is mixed with acid and added to an alkaline pulp the mica will be prevented from entering the froth, i. e. be depressed.

When starch and sodium cyanide are added to an alkaline pulp, the sulphides are depressed and' the mica floated and the higher the alkalinity, the lessof the other minerals and the more of the mica that isfloated.

When it is desirable to float mica in preference to sulphides, the ore must be ground fine enough to free the minerals and mixed with from one to siX parts of water; at this point the pulp should be made distinctly alkaline, preferably with lime to about .3 lbs. of lime per ton of Water; then add sufiicient starch and cyanide to prevent the sulphides from floating, then add about .05 lbs. of pine oil per ton of ore and float, removing the mica with the froth. The amount of cyanide and starch needed depends on the composition of the ore.

The more sulphides present the larger the quantity of starch and cyanide needed.

Two examples to show the effects mentioned above are as follows:

A. A mixed copper mica concentrate in a pulp containing .3 lbs. of lime per ton of water was treated with .4 lbs. of starch and 2/l0th lbs. cyanide per ton of ore and floated with results as follows:

Per cent Per cent Cu mica Heads 7. 0 50. 0 Concentrates 1. 9 80. 0 Tails 13. 9 10. 0

B.- An ore was ground with sufiicient lime and four parts of water to give an alkalinity of .2 lbs. per ton of water, .8 lbs. of starch and .2 lbs. of cyanide and .05 lbs. of pine oil per ton of ore were thenadded to the pulp and the mica removed with the froth.

Per cent Per cent Ou mica made 2.0 35.0 Concentrates 2 83. O Tails 1.9 5.0

In flotation, it is at times necessary to float the ore in a neutral or acid pulp and with other ores, an alkaline pulp is used to produce the best results. When the pulp is neutral or acid the addition of starch alone is suflicient to depress the mica; if the pulp is alkaline it is necessary to add acid and starch to depress the mica which greatly increases the cost.

Equal weights of starch and sulphuric acid are used as the additional agent by us but we have found the proportion may be widely varied and still obtain satisfactory results. As examples, an ore containing.1% copper and mica was treated as follows: The ore was ground with 3 lbs.of lime per ton andya weight of water equal to that of the ore, additional water, was then added to give a dilution of three parts of water to one part ofore, this pulp which showed an alkalinity of .2 lbs. per ton was subjected to a flotation treatment to obtain a copper con centrate in the usual manner, i. e. .03 lbs. of pine oil and .2 lbs of xanthate were added and a froth was removed, this froth-contained copper sulphides, iron sulphides, mica and other substances. .The products were as follows: J V

Per cent r p Per cent Cu mica Froth 8. 0 40. 0 Tails v 2 6 The froth was treated in three ways for comparison asto value of difierent treatments with. starch, the object being to so treat the pulp that when it was refloated in a flotation machine, a high grade Cu concentrate could be removed with the froth and the bulk of the mica would be found in the residue.

g .3 lbs. of starch added in a 1% solution per ton of original mill feed Was added to the froth which was then refloated. This gave a froth assaying 10% Cu, 45% mica and tail- ..-ings assaying 1% Cu and 10% mica.

"BI/10th lbs. of'starch arid .3 lbs. of sulphuricacid per ton of original mill feed were mixed into a 1% solution and this solution has added to thefroth which was then refloated.

This gave a froth assaying 20% Cu, 8% mica lbs. per ton of ore. Enough starch must be used to depress the mica. This depends on the tures.

requires different amounts and sometimes different kinds of reagents depending upon its composition. Even the ore produced from the same mine on diflerent-days requires different amounts of reagents.

'In a strongly acid pulp by proper additions of acid and starch, the mica and'to a considerable extent the iron pyrites are prevented from floating so that only the more valuable sulphides are floated.

When a solution of starch is mixed with a small amount of acid or acid substance and this solution added to an alkaline or strongly alkaline pulp, the mica is depressed and the sulphides floated the same as if the pulp was acid or neutral and this occurs iii the alkaline pulp in amuch more efiicient manner than without the addition of acid to the starch previous to its addition'rto the pulp..

What we claim, is e 1. In a froth flotation process, the method of separating micaceous and talcy minerals from sulphides comprising the addition of starch and cyanide to an alkaline pulp to cause the said minerals to enter the froth and to prevent the sulphides from so doing, and then subjecting-the ore pulp to froth flotation;

2. In a froth flotation process, the method of treating a mass of pulp and ofseparating the micaceous and talcy minerals from the concentrates therein, which comprises establishing a desired alkaline reaction in said pulp mass, adding a quantity of starch and a reagent 'to depress the concentrates and cause ceous and talcy minerals which comprises es-' tablishing an alkaline reaction in the presence of starch to cause the micaceous minerals to enter the froth and subjecting the mass while alkaline to froth flotation.

In testimony whereof, we aflix our signa- R; E. PHELAN. ySHERWIN P. LOWE.

' in the pulp to have a strongly acidreacti'on.

the amount'neededmay vary from 1 lb. toTOO amount present and-its tendency to float and may vary from .01 lbs. to2 ormore lbs. per

ton of ore and can determined by expe'ri-' ment. I p

' There are a great number of acids and alkalies which will produce the efiects above mentioned and thechoice of anyparticular one is governed bylocal circumstances as every ore 10o the micaceous and talcy minerals to enter 

